How to Add a BlackBerry to an Enterprise Server
- 1). Open the "Settings" dialog from the main BlackBerry menu, then scroll down and select "Options." Select "Advanced Options" in the following menu.
- 2). Scroll down and select "Enterprise Activation" to begin. Enter your email address and account password for the BES. This should be provided by your IT department.
- 3). Press down once to open a menu, then scroll to select the "Activate" option. You may need to plug the BlackBerry in to maintain a charge while all of your contact and email information is synchronized with the device.
Source...